Glass front vending machines are machines designed for vending articles of various sizes and shapes, including packaged snack foods, merchant cards, and consumer articles. These machines generally have a selector panel, located off to one side of the glass front, and use some form of horizontal trays, partitioned into columns, to store the articles to be vended.
Typically, after a consumer makes the requisite payment and enters the desired selection on the selector panel, the forward-most article from the selected column is ejected or dislodged, and the article drops freely into a delivery hopper at the bottom of the machine. The space that the article falls through is the area between the fronts of the columns and the back of the glass front, commonly referred to as the vend space.
It is important that vending machines operate in a reliable manner and provide consumers with the selected article without the need to expend unusual effort to obtain the article. With this said, there exists various events that can compromise the reliability of vending machine operations. For example, the spatial orientation and wrinkling of packages, the content distribution of packages, the tumbling of packages through the vend space, and empty spiral pockets can all contribute to the mis-vending of articles.
Various detection schemes have been employed to detect when an article passes through the vend space. These all suffer from various shortcomings, including failing to detect smaller articles that escape through an electromagnetic beam or multiple beams or failing to impart sufficient force on impact or vibration on a sensor located at the bottom of the vend space.